Page 300 - Ganit Kaushal

2. 3. (a) 28 (b) 14 (c) 7
4. (a) → (iii) (b) → (iv) (c) → (i) (d) → (ii)
5. 6, 4
6. (a) Yes, all are multiples of 3
(b) Yes, all are multiples of 4
(c) All are multiples of 12
7. (a) HCF = 4, LCM = 308 (b) HCF = 13, LCM = 572
Exercise 5.2
1. 105 = 3 × 5 × 7

2. None; since if 2 or 4 are at unit’s place, then it is
even, hence composite. If 5 is at unit’s place then it is
divisible by 5.
(a) 30-44 and 45-59; 1,20,000 3. 2 × 2 + 1 = 5 (Prime); 2 × 5 + 1 = 11 (Prime);

(b) 1,20,000 2 × 11 + 1 = 23 (Prime); 2 × 23 + 1 = 47 (Prime);
3. Do it yourself. 2 × 41 + 1 = 83 (Prime).

4. (a) 1 unit length = `5000 profit 4. Smallest difference = 1 (between 2 and 3); Largest
(b) In the year 1977; `20,000 difference = 8 (between 89 and 97).

(c) In the year 1979, `13,000 5. No; The decade 91-100 has the least number of primes,
5. (b) 6. (d) 7. (a) 8. (b) only 1.
9. (a) 10. (c) 11. (a) 12. (b) The decade 1-10 and 11-20 has the maximum number
of primes, 4 primes.
13. (a) raw (b) primary 6. No. ( All other even numbers are divisible by 2).
(c) secondary (d) frequency 7. (a) Prime number (b) Composite number
14. (a) False (b) True (c) False (d) False (c) Prime, Composite number
(e) False (f) True (d) 2 (e) 4
Assertion Reason 8. (a) False ( 1 + 3 + 5 = 9)
1. (b) 2. (a) 3. (a) 4. (a) (b) True (c) True (d) False    8 = 4  
5. (c) 6. (d) (e) False ( 2 is an even number)  2 
Chapter Test (f) False ( 1 is the factor of prime numbers)
I. 1. (i) (d) (ii) (a) (iii) (b) (iv) (b) (Answer may vary)
(v) (c) 9. (a) 29 (c) 43 (d) 61
2. (d) 3. (a) 4. (a) 5. (b) 10. (a), (b), (c), (e)
6. (c) 11. (a) 24 = 5 + 19 (b) 36 = 7 + 29
II. 1. 13 2. equal 3. frequency 4. 28 (c) 84 = 17 + 67 (d) 98 = 19 + 79
5. 120 6. ||| (Answer may vary)
III. 1. True 2. False 3. True 4. False 12. (a) 24 = 11 + 13 (b) 36 = 17 + 19
5. False 6. True (c) 84 = 41 + 43 (d) 120 = 59 + 61
IV. 1. (a) 25 (b) 25 13. (a) 21 = 3 + 7 + 11 (b) 35 = 5 + 11 + 19
(c) 175 (d) Wednesday (c) 49 = 7+ 11 + 31 (d) 63 = 7 + 13 + 43
2. (a) 1 unit = 10 marks (b) Mathematics 14. (2, 3), (2, 13), (3,17), (7, 13), (11, 19)
(c) Hindi (d) English Exercise 5.3
1. Co-prime
Chapter 5: Prime Time 2. Not divisible
Exercise 5.1 3. (a) 2 × 2 × 2 × 2 × 2 × 2 (b) 2 × 2 × 2 × 13
1. (a) 1, 5 (b) 1, 2, 4, 8 (c) 5 × 3 × 7 (d) 3 × 3 × 3 × 3 × 3
2. 72, 96 4. 2 × 2 × 3 × 3 × 3 × 5 × 5 × 3

298 Mathematics-6